COLOR CONTRAST THRESHOLDS ARE NORMAL IN FUNCTIONAL AMBLYOPIA

We evaluated colour contrast thresholds in patients with unilateral fu nctional amblyopia, A computer-controlled colour vision test was used to determine colour contrast thresholds along a blue-yellow tritan axi s, Prior to the threshold measurement, a heterochromatic flicker brigh tness test was performed to ensure isoluminance between the test stimu lus and the background for every subject individually, Luminance contr ast thresholds were also measured using the same computer-based system , Twenty amblyopic patients were tested, All showed normal tritan colo ur contrast thresholds both for their amblyopic eye and non-amblyopic fellow eye, Luminance contrast thresholds were elevated in all 6 refra ctive amblyopic eyes, in 4 of 9 strabismic eyes and in 2 of 5 mixed am blyopic eyes, Colour contrast thresholds are normal in functional ambl yopia (with central fixation). Whenever elevated tritan colour contras t thresholds are found in patients with a decreased visual acuity, oth er causes of visual impairment are to be evaluated.